Partialsynthetische Aristolochiasäuren und ihre Homologen,II. Mitt.: 3,4,6,7-Tetramethoxy-10-nitrophenanthren-1-carbonsäure

A new method for the synthesis of aristolochic acids and their homologues was presented. According to the above procedure 3,4,6,7-tetramethoxy-10-nitrophenantrenecarboxylic acid was obtained from a product of glaucine degradation and its chemical structure was proved.     

Der massenspektrometrische Zerfall von Hexamethoxydisilan und Oktamethoxytrisilan

The decomposition (70 eV, 17 eV) of Si₂(OCH₃)₆, Si₂(OCD₃)₆, and Si₃(OCH₃)₈ by electron-impact is characterized by an initial loss of the radicals CH₃, Si(OCH₃)₃, and OCH₃. For the disilanes, a typical pathway follows by successive loss of formaldehyde forming SiH-units; in the trisilane the main fragmentation path shows elimination of dimethoxysilylene previous to CH₂O-abstraction. Fragmentation schemes are given, in part metastable supported.     

Ion exchange removal of calcium carbonate and gypsum from mineral material prior to determination of cation exchange capacity using89Sr++

Summary The aim of the present work was to show that ion exchange resins can be used to remove sparingly and slightly soluble salts from calcareous and gypseous soils, which may otherwise cause serious errors in the determination of cation exchange capacity. It was shown that CaCO₃ and CaSO₄-2H₂O can be removed from a mixture with montmorillonite(Ca++) by a mixed bed resin. After resin treatment of the mixture its C.E.C. as retained Sr⁺⁺ corresponds approximately to the C.E.C. for pure montmorillonite within certain limits. Use of an anion exchange resin alone for removing these salts, however, gave an Sr⁺⁺ retention well below the C.E.C. for the mineral. It was assumed that this results from the blocking of exchange sites by resin particles.

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Zusammenfassung In kalkhaltigen und gipshaltigen B?den st?ren CaCO₃ und CaSO₄-2H₂O die Bestimmung des Kationenaustauschverm?gens. In der vorliegenden Arbeit wird gezeigt, da? Salze wie CaCO₃ und CaSO₄-2H₂O aus Mischungen mit Ca-Montmorillonit durch Ionenaustauscher herausgel?st werden k?nnen. Als Ionenaustauscher müssen jedoch Mischbettaustauscher verwendet werden; Anionenaustauscher allein liefern bei einer anschlie?enden Bestimmung des Kationenaustausches mit Sr⁺⁺ falsche Werte. Die angegebene Methode erscheint vor allem für die Untersuchung von B?den wichtig zu sein.

     

Photolyse von Monophenylphosphat und e aq − -Bildung in wäßriger Lösung

At photolysis (253.7 nm) of monophenylphosphate (10^?3 m) in O₂-free neutral aqueous solution were determined: orthophosphate (Φ=0.006), phenol (Φ=0.0029), besides of small amounts of phosphorous acid, benzene, 2.2′-dihydroxybiphenyl and traces of 2.4′- and 4.4′-dihydroxybiphenyl. The yield of the main products is smaller at pH 2 and 12. Polymers were formed at u.v.-doses >2·10¹⁹ hv/ml. The electron yield determined by means of N₂O increases from Φ (N₂)= Φ(e _aq ^? )=0.012 to 0.019 changing the ester concentration from 0.001 to 0.1m. Φ (N₂)-value rises by addition of methanol or increasing pH. As electron ejecting state an excited complex is postulated. The effective ionization potential of phenylphosphate in aqueous solution is ≦4.9 e.v.     

Zum Mechanismus der Hydrogenolyse aromatisch gebundenen Halogens

The selective chlorination of a m/p-xylene mixture, followed by distillation of the unreacted p-xylene, leaves a residue containing up to 90% of monochlorinated m-xylenes. m-Xylene is recovered from the latter by heterogeneous catalytic hydrogenolysis in the gas-phase. It was found that the hydrogenolysis on certain noble metal catalysts proceeds according to an ionic reaction mechanism at temperatures below a definite temperature range. At temperatures above this range hydrogenolysis follows a radical reaction mechanism.     

1,3,6-Triphenyl-6-phenylazo-1,4,5,6-tetrahydropyridazin

Base induced 1.4-elimination of pyridine·HI from 1-(2-phenyl-2-phenylhydrazono-ethyl)-pyridinium iodide (6) yields 1.3.6-triphenyl-6-phenylazo-1.4.5.6-tetrahydropyridazine (8) the (4+2)-cyclodimer of the intermediate 1-phenyl-1-phenylazoethylene (7).8 can also be obtained by intramolecular oxidative cyclisation (with KMnO₄) of 1.4-diphenylbutane-1.4-dione bisphenylhydrazone (12). Spectroscopic data (ms,¹H-nmr, uv and ir/Raman) confirm the structure of8.     

Kinetik der Diazotierung der Chloraniline in methanolischer Chlorwasserstofflösung

The kinetics of the diazotization of o-, m-, p-chloroaniline in 0.005n- to 0.4n-methanolic HCl-solution at 25, 15, 0, ?10 ?20, and ?30°C was invertigated. It was found that the nitrosation reaction (the same as in¹) $$C_6 H_4 ClNH_2 + NOCl \mathop \rightleftharpoons \limits^k C_6 H_4 ClNH_2 NO^ + + Cl^ - $$ is a proceeding advance-back-reaction. The decomposition of C₆H₄ClNH₂NO⁺ by splitting off a proton is the rate determining step. The free activation enthalpies ΔG ^* for the nitrosation reaction, the activation entropies ΔS ^*, the activation enthalpies ΔH ^* and the activation energiesE _a at the given temperatures are calculated. The experimentally found and the calculated velocities are given in Tables 1–6. The equilibrium constants of the o-, m-, p-chloroanilinium ions, and nitrosyl-chloride in methanol are indicated in Table 7, diagram 1. TheK _M values (the ionic products of methanol, extrapolated at infinite dilution) together with theK _A values of Table 7 give theK _B values (p. 2) using the table¹⁰. The ΔG _B values can be calculated using equation ΔG _B = ?RTlnK _B Fig 2 shows the linear dependance of the logarithmus of the ΔG ^* values from the logarithmus of theK _B values.     

IR- und Raman-Spektren einiger Kaliumpentafluorometallate-monohydrate

The IR- and Raman Spectra of several compounds of the stoichiometryM ₂ ^I M ^IIIF₅H₂O and their deuterated analogs have been interpreted on the basis of their crystal structures. The compounds studied were divided into two classes regarding the bonding of water molecules. The main spectroscopic difference between the two classes was found in the region of H₂O vibrations in good agreement with theoretical predictions. The metal—fluorine and metal—oxygene vibrations gave no direct information concerning the two types of water.     

Über die Synthese von 5-(o-Trifluormethylphenyl)-1H-thieno[3,4—e]-1,4-diazepin-2(3H)-onen

The synthesis of 5-(o-trifluoromethylphenyl)-1H-thieno-[3,4-e]1,4-diazepin-2(3H)-one (7) and its nitration and chlorination in pos. 8 are described.